Smartphones and everything that comes with it are more dangerous in that regard, in that a lot of activities on there are designed to give you a sense of accomplishment - finishing a level, getting an award, getting upvotes on the internets, winning at something, being moderately entertained by an endless stream of memes, dog / cat videos, etcetera. It's a continuous stream of short lived distractions.

Disclaimer: I use the phone all the time, Reddit takes up a lot of my attention. That said, I managed to sit down and read a book for a bit yesterday.